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Affiliation(s)
- R. A. Sack
- a Department of Theoretical Physics , University of Liverpool and British Rayon Research Association , Manchester
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Abstract
The defense of the ocular surfaces presents an unique challenge in that not only must integrity be maintained against microbial, inflammatory and physical assault, but it must be done while minimizing the risk of loss of corneal transparency. This puts severe limitations on the degree to which scarring or neovascularization can occur in the cornea secondary to any infectious, inflammatory, immunological or wound healing process. Moreover, this defense system must be equally effective under two extremes of conditions: those found in the open eye and the closed eye environments. It is our contention that these constraints have resulted in the evolution of a highly complex fail-safe defense system that utilizes distinctly different strategies in open and closed eye conditions. The extraordinary effectiveness of this system is evidenced by the fact that despite continued exposure to a microbe rich environment, the external ocular surfaces maintain a very low microbial titer and are highly resistant to breaching by all but a few pathogens. It is the intent of this review to provide a working model of this defense system as it operates under both open and closed eye conditions, to provide evidence in support of this model as well as highlight some of the many areas of uncertainty.
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Affiliation(s)
- R A Sack
- SUNY College of Optometry, Manhattan, New York 10036, USA.
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Abstract
Although the tear film has been extensively studied as it exists in the open eye state, until recently very little was known as to what happens to the tear film on eye closure. Recent studies have shown that eye closure results in a profound change in the composition, origins, turnover and physiological functions of the tear film. These changes include a shift from an inducible, neurologically controlled, lacrimal secretion containing among other proteins primarily lysozyme, lactoferrin and tear specific lipocalin, to a much slower, constitutive-type of secretion, composed almost exclusively of sIgA. This change is accompanied by the build-up of sialoglycoproteins of epithelial and goblet cell origin, the build-up and activation of complement and the build-up of serum proteins. In addition, various cytokines and proinflammatory mediators accumulate, including some which are potent inducers of angiogenesis and leukochemotaxis. The closed eye also exhibits the recruitment and activation of massive numbers of PMN cells. This results in a stagnant, closed eye layer, which is extremely rich in reactive complement products, PMN cell proteases including protease-3, elastase, capthepsin G, MMP-9 and urokinase. We have postulated that this shift represents a fundamental change in host-defense strategies from a passive-barrier defense to an active immune, inflammatory, phagocyte-mediated process and that this shift is necessitated in order to protect the cornea from entrapped microorganisms. Studies have shown that autologous cell damage is avoided in closed eye tear fluid, by the accumulation of several modulators of complement activation, which shift activation towards opsonization of entrapped microorganisms and the build-up of a wide array of antiproteases. Some of the latter are likely to arise from the ocular surface tissues. Corneal neovascularization may be avoided in part by the build-up of alpha2-macroglobulin and the conversion of plasminogen to angiostatin. It is highly probable that other bioactive protein fragments are produced in the closed eye, which contribute to homeostasis. Areas of future study are indicated.
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Affiliation(s)
- R A Sack
- SUNY, College of Optometry, 100 East 20 Street, Manhattan, NY 10010, USA
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Affiliation(s)
- N A McNamara
- Morton D. Sarver Laboratory for Cornea and Contact Lens Research, School of Optometry, University of California, Berkeley, USA
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Abstract
PURPOSE Although overnight eye closure is known to result in hypoxia and release of potent angiogenic factors, even prolonged eye closure does not result in corneal neovascularization. This suggests that the closed eye tear film may contain factors that can impede neovascularization. Closed eye tear fluid is known to contain proteases capable of converting plasminogen/plasmin to angiostatin and other angiostatin-like A-chain fragments which are potent inhibitors of angiogenesis. This study was designed to characterize open and closed eye tear fluid for the presence of these entities. METHODS Open and closed eye tears were collected by microcapillaries from normal individuals. Tears were centrifuged and the supernatants analyzed by SDS-PAGE and western blotting. Membranes were probed with antibodies specific for the A-chain of plasmin and plasminogen and with antibodies specific for conformational domains on the smaller N terminal kringles 1-->4 and kringles 1-->3 fragments which are known angiogenesis inhibitors. Supernatants were also analyzed after fractionation by HPLC and binding to lysine sepharose 4B. The isolated fragments were identified based on size, lysine-binding capabilities, antigenic properties and by comparison with standards. RESULTS Open eye tear fluid from all normal individuals contained low levels of plasminogen, but no detectable antigens consistent with free A-chain or angiostatins. Tears collected after overnight eye closure contained significant amounts of plasminogen, A-chain antigen and various A-chain fragments including kringles 1-->4 and kringles 1-->3 and most likely free kringle 5, all known to have anti-angiogenesis properties. These were often present in concentrations likely to be physiologically significant. In samples collected from an atopic subject, the concentration of angiostatins in CTF increased markedly during active phases of the disease reaching levels of several ng/microl. In these instances and in similar samples obtained from other atopic individuals experiencing active reactions, angiostatin was often detectable in basal-type tear fluid. CONCLUSION A-chain fragments, which can inhibit angiogenesis, are often present at physiologically significant levels in human tear fluid collected after overnight eye closure. These fragments may play a role in preventing neovascularization in the hypoxic closed eye environment and may well be up regulated during inflammatory reactions.
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Affiliation(s)
- R A Sack
- SUNY College of Optometry, New York, NY 10010, USA.
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Sack RA, Bogart B, Sathe S, Beaton A, Lew G. Characterization and origin of major high-molecular-weight tear sialoglycoproteins. Adv Exp Med Biol 1998; 438:235-8. [PMID: 9634892 DOI: 10.1007/978-1-4615-5359-5_34] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- R A Sack
- SUNY State College of Optometry, New York, New York, USA
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Sakata M, Beaton AR, Sathe S, Sack RA. 31-27 kDa caseinolytic protease in human tears. Adv Exp Med Biol 1998; 438:665-7. [PMID: 9634952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- M Sakata
- Department of Biological Sciences, State University of New York, State College of Optometry, New York, USA
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Sathe S, Sakata M, Beaton AR, Sack RA. Identification, origins and the diurnal role of the principal serine protease inhibitors in human tear fluid. Curr Eye Res 1998; 17:348-62. [PMID: 9561826 DOI: 10.1080/02713689808951215] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE Previous work identified polymorphonuclear leukocyte (PMN) elastase as the major caseinolytic entity in tears collected after overnight eye closure. This study was designed to identify the principal serine protease inhibitors (serpins) in tears and to determine their function in the regulation of PMN cell proteases on eye closure. METHODS Reflex and closed eye tear samples were collected by microcapillary tube and centrifuged. After reflex and closed eye supernatants (R and C) were fractionated by HPLC, samples were subjected to casein zymography and reverse zymography. Western blots were utilized to screen tears and HPLC fractions for elastase, cathepsin G and proteinase-3 and to obtain semi-quantitative data on alpha 1-protease inhibitor (alp1), alpha 1-antichymotrypsin (alpha 1-Achy), secretory leukocyte protease inhibitor (SLPI), elafin and alpha 2-macroglobulin (alpha 2-M) as well as associated complexes and products. To confirm specificity of reactivity, samples were immunoprecipitated for a given protease or serpin and screened for the coprecipitation of interacting species. RESULTS Although R fluid contains no caseinolytic activity, it contains low levels of serpin-like activity principally in the form of SLPI (5-10 ng/microliter). Lesser amounts of alpha 2-M, alpha 1-Achy and alp1 (approximately < 1-3 ng/microliter) are also evident. C fluid is associated with very high levels of PMN cell proteases along with a approximately 5-20-fold increase in the concentrations of all of the above inhibitors. Trace levels of elafin were also detected. The concentrations of rapid reacting inhibitors exceeded that of proteases, with SLPI, alpha 1-Achy and alp1 being the principal functional entities. In atypical samples, complexes of elastase and alpha 2-M were also encountered. CONCLUSIONS SLPI, a known antimicrobial agent and an elastase and cathepsin G inhibitor, is the principal serpin in R fluid. C fluid is associated with a marked increase in the concentrations of an array of rapid reacting serpins capable of inhibiting all known PMN cell serine proteases. In the normal closed eye, the concentration of rapid reacting inhibitors always exceeds that of proteases with C fluid also containing a functional reserve of the slow reacting inhibitor alpha 2-M.
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Affiliation(s)
- S Sathe
- SUNY, College of Optometry, NY, USA
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Abstract
PURPOSE To characterize the effects that mode of sampling and overnight eye closure have on the nature of caseinolytic activity recovered in tear fluid. METHODS Reflex, open and closed (R, O and C) eye tear fluids were collected by microcapillary tubes or from the inferior formix by Schirmer strip. Microcapillary collected samples were centrifuged and recovered cells cytochemically characterized and probed by immunofluorescence microscopy, or alternatively extracted in acidic PBS. Tear supernatants, pellets and Schirmer strip extracts were subjected to casein zymography or SDS-PAGE and immunoprobed for plasmin/plasminogen. To identify caseinolytic activity, samples were immunoprecipitated with antibodies to plasmin/plasminogen or to elastase, and the immunoprecipitated materials were subjected to zymographic analysis. RESULTS Immunoblot assays revealed R and O samples contained low levels of plasminogen (approximately 1.1 micrograms/ml) and only trace levels of plasmin (< 0.1 ng/ml). Insufficient levels of caseinolytic activity were present to allow zymographic detection. Cytochemical analysis revealed that R and O pellets consisted almost exclusively of desquamated epithelium. Immunoblot analysis revealed that C fluid was associated with an increase in plasminogen and its partial conversion to plasmin (approximately 3.2 ng/ microliter), high molecular weight covalent complexes and degradative products. Zymographic analysis disclosed much greater caseinolytic activity than could be attributed to plasmin or its cleavage products. This consisted primarily of three bands (30-26 kDa) which were identified as polymorphonuclear leukocyte (PMN) cell elastase based on size and antigenicity. This is derived from PMNs recovered from the C pellet. Elastase could also be recovered from Schirmer strips from 90% of donors, provided that the strips were extracted in sample loading buffer. The activity was restricted to the portion of the strip that had been in contact with the ocular tissue. CONCLUSIONS The main source of caseinolytic activity in C fluid is elastase. This arises from PMNs that undergo recruitment, activation and degranulation in the C environment. In contrast, the elastase recovered in Schirmer strip extracts is derived from intact PMNs that adhere to the strip during sample collection. This would suggest that PMN cells undergo a low level of recruitment into the open eye environment.
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Affiliation(s)
- M Sakata
- State University of New York, College of Optometry, Department of Biological Sciences, NY 10010, USA
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Sack RA, Bogart BI, Beaton A, Sathe S, Lew G. Diurnal variations in tear glycoproteins: evidence for an epithelial origin for the major non-reducible > or = 450 kDa sialoglycoprotein(s). Curr Eye Res 1997; 16:577-88. [PMID: 9192167 DOI: 10.1076/ceyr.16.6.577.5069] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE To characterize the nature and origin of changes in tear glycoproteins accompanying eye closure. METHODS Reflex (R) and overnight closed (C) eye tears collected by capillary tubes were centrifuged with the resulting R pellets (primarily desquamated epithelial cells) and C pellets (primarily PMN and some epithelial cells) extracted in acidic PBS. Extracts and supernatants were separated by size-exclusion HPLC and/or SDS-PAGE. Gels were stained or blotted and immune- or lectin-probed. An HPLC glycoprotein fraction of > or = 450 kDa isolated from all four sources was characterized before and after partial deglycosylation, using antibodies specific to known mucin and carbohydrate epitopes. Immunofluorescence microscopy was carried out on human conjunctiva, using as probe a MAb to salivary mucin specific for a sialyl Lea epitope, which was found to cross-react specifically with the major non-reducible high molecular weight sialoglycoproteins (SGs) in tears. These SGs were immunoprecipitated and blot-probed along with tissue extracts. RESULTS R fluid contained minor amounts of numerous glycoproteins, including probably several of inducible lacrimal secretory origin. Results confirmed sIgA as the principal source of the intense reducible glycoprotein bands common to C fluid. Smaller amounts of free secretory component and serum glycoproteins were also visualized. The HPLC fraction (> or = 450 kDa) consisted of four major non-reducible glycoproteins. In R fluid, this fraction (< 1% total protein) consisted primarily of two entities: a 450-500 kDa SG and a larger asialoglycoprotein. The SG accounts for as much as 85% of the total protein in the R pellet extract. C fluid was associated with a selective increase in SGs and a shift in distribution to two SGs > 500 kDa. All SGs exhibited a common antigenicity reacting specifically with the MAb for the sialyl Lea epitope. SGs indistinguishable in size and antigenicity were recovered in epithelial extracts. Immunofluorescence microscopy revealed that reactivity was localized to the epithelial plasma membrane, increasing in intensity from basal to apical cells. Although these SGs exhibited some properties in common with MUC1, immunological and other data suggest a unique SG. CONCLUSIONS Tear glycoproteins are derived from four principal sources. In R fluid, an inducible lacrimal secretion predominates. In C fluid, a constitutive sIgA secretion predominates, augmented by a serum exudate and SGs derived at least in part from the epithelium. In R fluid and pellet extracts, the SGs consist primarily of a 450-500 kDa species that is most probably derived from the plasma membrane. Larger antigenically related SGs are prevalent in C fluid.
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Affiliation(s)
- R A Sack
- State College of Optometry, State University of New York, Manhattan 10010, USA
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Willcox MD, Morris CA, Thakur A, Sack RA, Wickson J, Boey W. Complement and complement regulatory proteins in human tears. Invest Ophthalmol Vis Sci 1997; 38:1-8. [PMID: 9008624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
PURPOSE The complement system is part of the innate defense system of the body, and it contributes to inflammatory conditions. The current study examined tears for the presence of complement components, the activity of the components, and the presence of regulatory components. METHODS The significance of a functional complement system in tears was examined in four ways. First, the presence and concentration of complement components in tear samples (open-eye, closed-eye, and reflex tears) was examined by sandwich enzyme-linked immunosorbent assay. Second, the presence of an active pathway in each tear type was established by supplementation of complement-deficient sera. Third, Western blotting of tear samples was used to determine whether complement components were activated in tears. Fourth, the presence of regulatory components was examined by enzyme-linked immunosorbent assay and by the inhibition of the ability of tears to supplement deficient sera. RESULTS Components C1q, C3, factor B, C4, C5, and C9 were detected in closed-eye tears. Only C3, factor B, and C4 were detected in open-eye and reflex tears. Tears were able to supplement complement-deficient sera, indicating that the components were in an active state. Complement components C3, factor B, C4, and C9 were activated in closed-eye tears. The regulatory protein decay-accelerating factor was found only in closed-eye tears. Lactoferrin, another regulatory protein present in all tear types, was shown to inhibit complement-mediated red blood cell lysis, although the inhibition by closed-eye tear lactoferrin was reduced compared to that isolated from other tear types. CONCLUSIONS This study has demonstrated that the complement system in tears was functionally active and that the concentration of all components was increased greatly in closed-eye tears. In spite of the presence of regulatory proteins, proteins of the complement cascade in tears were shown to be activated.
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Affiliation(s)
- M D Willcox
- Cornea and Contact Lens Research Unit, University of New South Wales, Sydney, Australia
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Sack RA, Sathe S, Hackworth LA, Willcox MD, Holden BA, Morris CA. The effect of eye closure on protein and complement deposition on Group IV hydrogel contact lenses: relationship to tear flow dynamics. Curr Eye Res 1996; 15:1092-100. [PMID: 8950503 DOI: 10.3109/02713689608995140] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE This study was designed to determine the effect of overnight eye closure on the rate and composition of protein deposition on high water content ionic matrix soft contact lenses (Group IV SCLs) and to extrapolate from this data information on the probable change in the rate of reflex-type tear secretion associated with eye closure. METHODS Group IV SCLs were temporally sampled after equivalent periods of wear under closed eye (C) or open eye (O) conditions. Lenses were rinsed in saline and the majority of the tightly bound protein extracted at 90 degrees C in 40% urea, containing 1% SDS, 1 mM DTT, 100 mM Tris-HCl (pH 8.00). Residual protein was determined by Coomassie staining of the extracted lenses and densitometric analysis. Extracted protein was quantitated and separated by SDS-PAGE. Gels were either stained with Coomassie blue or reversibly stained with imidazole-zinc and blotted. Blots were PAS stained, or lectin and antibody probed for glycoproteins, secretory IgA (sIgA), IgG, lysozyme and complement C3. Laboratory simulated deposition studies were carried out on unworn lenses exposed to HPLC purified lysozyme. RESULTS The protein in the saline rinse, to a large degree mirrored the composition of tear fluid in which the lens had been residing (O or C). This would suggest that the saline wash consists of residual tear fluid and loosely adherent protein. In contrast, the urea extracts were highly homogeneous consisting primarily of lysozyme and to lesser extent lysozyme dimer. This supports the contention that the Group IV SCL functions in the eye much as cationic exchange resin selectively absorbing lysozyme. C extracts also proved relatively enriched in trace amounts of sIgA, IgG and complement C3 and its breakdown products. High levels of C3 and C3 breakdown products were specifically recovered only in the C worn lens extracts from a subject experiencing unilateral contact lens associated corneal infiltrates from the affected eye. In all subjects, markedly less protein (lysozyme) was recovered in urea extracts of lenses exposed to 7-8 h of closed eye as compared to open eye wear (0.20 +/- .08 versus 0.79 +/- .15 mg/lens (n = 6)). Temporal studies further revealed that deposition was linearly related to duration of wear during the initial phase of conditioning film formation giving rise to rate constants for lysozyme deposition of 2.2 +/- 0.29 (n = 5) and 0.20 +/- 0.06 microgram/min (n = 4) under open and closed eye conditions respectively. With further wear, deposition eventually reached a steady state. Under laboratory conditions, lysozyme was much rapidly and quantitatively removed from solution in a manner following a hyperbolic plot. This suggests that during the initial phase of deposition the rate of deposition is limited by the capacity of the tear fluid to deliver lysozyme to the lens surface under these two extremes of conditions. CONCLUSIONS Eye closure profoundly affects the rate of lysozyme deposition on Group IV hydrogels and the composition of minor biofilm constituents in a manner that could affect biocompatibility. Findings support the contention that eye closure results in a > 90% reduction in the rate of reflex-type tear secretion.
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Affiliation(s)
- R A Sack
- Department of Biological Sciences, State College of Optometry, State University of New York, NY 10010, USA
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Sack RA, Underwood A, Tan KO, Morris C. Vitronectin in human tears--protection against closed eye induced inflammatory damage. Adv Exp Med Biol 1994; 350:345-9. [PMID: 7518183 DOI: 10.1007/978-1-4615-2417-5_59] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Affiliation(s)
- B A Holden
- Cornea and Contact Lens Research Unit, School of Optometry, University of New South Wales, Sydney, Australia
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Abstract
Overnight eye closure induces a shift in the nature and composition of the tear film, from a dynamic reflex tear-rich to a stagnant secretory IgA-rich layer. This is accompanied by the induction of a state of sub-clinical inflammation, as evidenced by increases in albumin levels, plasminogen activation, conversion of complement C3 to C3c, and the recruitment of polymorphonuclear (PMN) cells into the tear film. To determine the time course and functional relationship between these potentially interdependent processes, tear samples were collected from ten non-contact lens wearers after 1, 2, 3 and 5 hours of sleep. A subgroup of 6 subjects also self-collected tear samples after 8 hours of sleep. Tear samples were analysed for albumin by quantitative immunofixation assay, secretory IgA (sIgA) by radial immunodiffusion assay, plasmin-like activity using a chromogenic substrate, and complement C3 to C3c conversion by immunoblot assay. Epithelial and PMN cells in the precorneal tear film were recovered from corneal washings from the same subjects after 1, 3, 5 and 8 hours of sleep, and quantified. Results revealed that, unlike epithelial cells which exhibited a slow progressive accumulation as a function of the period of sleep, PMN cell concentration exhibited a lag phase, with recruitment occurring after between 3 and 5 hours of eye closure. This was preceded by plasminogen activation, increases in albumin and sIgA levels, and complement C3 to C3c conversion, all of which occurred within 1 to 3 hours after eye closure. Plasmin-like activity appeared to plateau after 3 hours and then decreased.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K O Tan
- Cooperative Research Centre for Eye Research and Technology, School of Optometry, University of New South Wales, Sydney, Australia
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Lipkin SM, Näär AM, Kalla KA, Sack RA, Rosenfeld MG. Identification of a novel zinc finger protein binding a conserved element critical for Pit-1-dependent growth hormone gene expression. Genes Dev 1993; 7:1674-87. [PMID: 8370519 DOI: 10.1101/gad.7.9.1674] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The growth hormone (GH) and prolactin genes require the pituitary-specific POU domain transcription factor Pit-1 for their activation. However, additional factors are necessary for the effective expression of these genes. Analysis of evolutionarily conserved sequences in the proximal GH promoter suggests the critical importance of one highly conserved element located between the two Pit-1 response elements. Mutation of this site decreases expression of a transgene in mice > 100-fold. We have identified a major activity binding to this site as a novel member of the Cys/His zinc finger superfamily, referred to as Zn-15. The Zn-15 DNA-binding domain comprises three zinc fingers separated by unusually long linker sequences that would be expected to interrupt specific DNA site recognition. Zn-15 synergizes with Pit-1 to activate the GH promoter in heterologous cell lines in which this promoter is only minimally responsive to Pit-1 alone. Our data suggest that functional interactions between the tissue-specific POU domain factor Pit-1 and this novel zinc finger factor binding to an evolutionarily conserved region in the GH promoter may constitute an important component of the combinatorial code that underlies the effective expression of the GH gene.
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Affiliation(s)
- S M Lipkin
- Eukaryotic Regulatory Biology Program, University of California, San Diego, La Jolla 92093-0648
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Sack RA, Tan KO, Tan A. Diurnal tear cycle: evidence for a nocturnal inflammatory constitutive tear fluid. Invest Ophthalmol Vis Sci 1992; 33:626-40. [PMID: 1544788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
To investigate the tear film in the closed eye, microliter tear samples were collected without overt reflex stimulation throughout the diurnal cycle, with closed eye samples recovered immediately upon eye opening. Samples were subjected to agarose, polyacrylamide, and two-dimensional electrophoresis, coupled with immunofixation, immunoblot, and lectin blot assays. Major protein constituents were densitometrically and immunologically quantified. Results revealed a distinct progression in composition from reflex to open to closed eye tear samples. Total protein increased from 6.0 to 9.0 to 18.0 mg/ml, secretory IgA increased from less than 0.23 to 0.85 to 8.40 mg/ml, and serum albumin increased from 0.02 to 0.06 to 1.10 mg/ml. In contrast, concentrations of the major reflex tear components (lysozyme, lactoferrin, and tear specific prealbumin) remained essentially static. Immunoblot assay for complement C3 and C3c revealed that eye closure was associated with C3 activation. Results indicate that: (1) the reflex and closed eye tear layers represent opposite extremes in composition and likely origins, with open eye tear film suggesting an intermediate origin; (2) reflex tears are derived from a neurologically inducible lacrimal or accessory gland secretion composed almost exclusively of lysozyme, lactoferrin, tear specific prealbumin, and a minor mixed alpha to beta globulin fraction; (3) upon eye closure, reflex secretion ceases or greatly diminishes, with ongoing slower flow maintained by a constitutive secretion composed almost exclusively of secretory IgA; (4) the closed eye environment induces a subclinical inflammation, accounting in part for the marked rise in albumin concentration. This increase, coupled with that of secretory IgA, may play a critical role in protecting the closed eye environment from pathogens. However, this may render the closed eye environment particularly vulnerable to inflammatory and immune-mediated pathological processes, such as those seen with extended wear soft contact lenses.
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Affiliation(s)
- R A Sack
- Cornea and Contact Lens Research Unit, School of Optometry, University of New South Wales, Sydney, Australia
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Sack RA, Harvey H, Nunes I. Disinfection associated spoilage of high water content ionic matrix hydrogels. CLAO J 1989; 15:138-45. [PMID: 2720948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Chemical analysis was carried out on clinically obtained hazy white hydrogel lenses that had been exposed to hydrogen peroxide disinfection. Analysis revealed that hazing was a surface phenomenon limited to high water content ionic matrix hydrogels (type IV), the type associated with the deposition of large amounts of lysozyme. We subjected unworn lenses to cycling studies involving doping in a variable artificial tear solution followed by exposure to disinfectant; this allowed us to duplicate the clinical situation and to derive a mechanism for this phenomenon. Hazing proved independent of the presence of hydrogen peroxide but dependent on the interaction of lens-bound lysozyme and stannate anion, the latter derived from sodium stannate present in the disinfectant as a stabilizing agent. Hazing is restricted to the type IV hydrogels because only these polymers have a sufficient number of anionic binding sites and are of sufficient porosity to allow the penetration and binding of a thick layer of lysozyme. Lysozyme is essential to hazing. No other tear protein is small enough to penetrate the hydrogel matrix or basic enough to have a marked affinity for the lens and to provide binding sites for stannate anion. These findings highlight the unique vulnerability of the type IV hydrogel to interaction with trace or transient ionic constituents in tears and lens care solutions.
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Affiliation(s)
- R A Sack
- Department of Biological Sciences, State College of Optometry, SUNY, NY 10010
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Abstract
Two small series of cases documenting ultrasound misdiagnoses are presented. The first concerns obstetric ultrasound misdiagnoses originating in the private offices of physicians. The second concerns gynecologic ultrasound misdiagnoses originating in a level II medical center. A dichotomy exists in the use of diagnostic ultrasound examination in the practice of obstetrics and gynecology. The dichotomy is a serious defect in our specialty that needs urgent addressing. The institutional problem can be partially resolved by furnishing the sonographer with the referred patient's history and physical findings. The problem of the ultrasound machine in the office of a private physician is much more complex. It may require government intervention and strict licensing measures for resolution.
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Affiliation(s)
- R A Sack
- Department of Radiology, Presbyterian Intercommunity Hospital, Whittier, CA
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Sack RA, Jones B, Antignani A, Libow R, Harvey H. Specificity and biological activity of the protein deposited on the hydrogel surface. Relationship of polymer structure to biofilm formation. Invest Ophthalmol Vis Sci 1987; 28:842-9. [PMID: 3570694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The in-situ lens-bound protein layer (LBPL) was characterized on hydrogels of varying water content and ionic-binding capacity. The LBPL proved to be critically dependent on the ionic binding capacity of a given hydrogel. On nonionic polymers the LBPL invariably was thin and largely insoluble. Histochemical staining allowed the detection of all major types of tear proteins. Amino acid analysis revealed a variable composition. Extractable protein proved devoid of active lysozyme. Electrophoresis of pooled samples revealed a variable mixture of acidic, neutral, and basic bands. To what extent variability is dependent on tear film composition and lens structure awaits use of more sensitive analytic procedures. On anionic hydroxyethylmethacrylate copolymer lenses, the LBPL proved radically different. Here the LBPL invariably was much thicker and composed primarily of loosely bound protein. Electrophoresis and enzymatic analysis revealed a homogenous layer consisting primarily of lysozyme much of which retains enzymatic activity. The amino acid analysis of the insoluble protein suggests a similar composition. Specificity of deposition can be attributed to ionic affinity. Conformational integrity can be attributed partly to the unique stability of lysozyme. Electrophoresis of a pooled anionic lens extract revealed an unknown, highly mobile, basic protein. This presumably represents the selective accumulation of a highly basic trace or transient constituent of the tear film. The specificity and biological activity of the LBPL on the anionic lens may modify hydrogel biocompatibility affecting risk of spoilage, microbial colonization, and propensity to trigger an inflammatory and immune response.
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Abstract
"Jelly bump" deposits, common to high-water-content hydrogel extended-wear contact lenses, were shown to be composed primarily of lipids, with calcium an optional minor component. Extraction, separation, and analysis of deposited versus nondeposited regions of the same lenses reveals that lipids were restricted to the deposited regions of the lens, with a composition of long and intermediate chain cholesterol esters (possibly waxy esters) and triglycerides. This composition is independent of deposit size or individual depositor. Except for an elevated triglyceride level, the composition mirrors that of the tear lipid layer. Analysis of tear films of heavy and nondepositors, combined with clinical evidence, reveals that many depositors have a relatively decreased tear flow with some exhibiting an elevated tear-lipid fraction. A mechanism of deposition is proposed to require the local depletion of the aqueous tear layer stranding lipid on the lens surface, thereby creating a hydrophobic region suitable for further deposition. Deposition does not mechanistically involve tear film proteins, calcium, or microorganisms although they can, at times, be associated with the lipid deposit.
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Abstract
During a 12-month period, 7933 surgical procedures were performed in a suburban intercommunity hospital. Thirty scheduled procedures were cancelled preoperatively by the anesthesia department because the level of serum potassium was below 3.2 mEq/L. Hypokalemia compromised three patients intraoperatively, and two patients suffered severe and life-threatening complications postoperatively. A preoperative bowel preparation produced severe hypokalemia in one patient, thus bringing the routine use of this time-honored procedure into question. The suggestion is made that all patients who are over 50 years of age, and who are scheduled for elective operation, receive an admission evaluation of the level of serum potassium.
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Lewy AJ, Sack RA, Singer CL. Assessment and treatment of chronobiologic disorders using plasma melatonin levels and bright light exposure: the clock-gate model and the phase response curve. Psychopharmacol Bull 1984; 20:561-565. [PMID: 6473662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Abstract
Over a 10-year period 12,643 gynecologic surgical procedures were performed with the patients under general anesthesia. Succinylcholine was the muscle relaxant used in the majority of cases. Four of these patients developed prolonged postoperative apnea; the longest period of apnea was 6 hours. In one patient atypical cholinesterase was documented, and two of the patients were subsequently diagnosed as having myasthenia gravis. In the fourth case an etiology for the apnea was not demonstrated. A compilation of drugs in common clinical usage which interfere with neuromuscular transmission is included.
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31
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Sack RA. Preparation of bovine rod outer segment membranes capable of regenerating visual pigment with added 11-cis-Retinol. Methods Enzymol 1982; 81:506-9. [PMID: 7098895 DOI: 10.1016/s0076-6879(82)81068-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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32
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Sack RA. The effect of utilization on health care costs. Am J Obstet Gynecol 1980; 137:270-5. [PMID: 7377246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This report analyzes the effect of utilization on health care costs. Two important aspects of utilization are examined: (1) the type of obstetric delivery utilized; (2) the extent of utilization of hospital facilities. A retrospective review of the type of delivery employed by five different physicians to deliver 494 primiparous patients revealed cesarean section rates varying from 16% to 40%. Average charges incurred by 100 patients who had undergone uncomplicated abdominal hysterectomies varied by as much as 26%. A simple formula to project cost is included.
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Abstract
Negligence and failure to "test timely" are the two most common charges in obstetric and gynecologic malpractice suits. Both charges are often made in cases involving urinary tract injury during gynecologic surgery. These injuries occur most commonly during abdominal hysterectomy. This report is a 6 year study of 170 consecutive abdominal hysterectomies to ascertain the value of routine preoperative urography in preventing urinary tract injuries. As a control, 260 consecutive abdominal hysterectomies were performed without preoperative urography. There was one ureteral transection in the control group, but unrecognized urinary tract injuries did not occur in either the study or control group. The risks, costs, and benefits of urography are analyzed.
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Abstract
This is a retrospective 5 year study of cancer detection in the suburban office of a primary-care physician. There were 127 diagnoses of malignancy confirmed in 5,011 patients, 62 in the reproductive system and 62 in other organ systems. More than 9,000 Pap smears resulted in the final diagnosis of carcinoma of the cervix in only seven patients. 374 curettages yielded 37 cases of endometrial carcinoma. All of these patients had Class I Pap smears preoperatively.
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38
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Sack RA. Bilateral internal iliac (hypogastric) artery ligation to control obstetric and gynecologic hemorrhage. A ten-year review at the community hospital level. Am J Obstet Gynecol 1973; 116:493-7. [PMID: 4541135 DOI: 10.1016/0002-9378(73)90905-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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39
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40
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Erlanger BF, Sack RA. Opertional normality of alpha-chymotrypsin solutions by a sensitive potentiometric technique using a fluoride electrode. Anal Biochem 1970; 33:318-22. [PMID: 5439485 DOI: 10.1016/0003-2697(70)90302-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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41
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Sack RA. The large infant. A study of maternal, obstetric, fetal, and newborn characteristics; including a long-term pediatric follow-up. Am J Obstet Gynecol 1969; 104:195-204. [PMID: 5305281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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42
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Erlanger BF, Buxbaum SN, Sack RA, Cooper AG. Operational normality of alpha-chymotrypsin solutions by coulometric-amperometric titrimetry. Anal Biochem 1967; 19:542-7. [PMID: 6048163 DOI: 10.1016/0003-2697(67)90244-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Sack RA, Maradudin AA, Weiss GH. Extension of the Range of Validity of Thirring's Expansion for the Specific Heat of Crystals. ACTA ACUST UNITED AC 1961. [DOI: 10.1103/physrev.124.717] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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48
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Abstract
The surface viscosity of soluble films can
be determined by measuring the velocity, vm,
of an element of surface moving along the centre-line of a rectangular trough
under the influence of a constant bulk flow, V, of solution along the trough.
An equation is derived in which the ratio, V/vm,
is described accurately in terms of the dimensions of the trough, the viscosity
of the solution, and the surface viscosity of the film adsorbed at the
air-water interface. This equation is based on the assumption that the surface
pressure gradient along the trough is zero. When the surface pressure gradient
is not zero, but is constant and of known magnitude, a second equation makes it
possible to determine the surface viscosity. ����� Measurements of surface viscosity have
been made with water, electrolyte solutions, and solutions of sodium dodecyl
sulphate and of n-octanol.
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49
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Abstract
A critical review of theories of the
frequency dependence of the dielectric constant of dipolar substances is given
and inconsistencies are pointed out in previous attempts to account for dipolar
interaction. A new theory is presented based on Debye's theory of molecular
relaxation and using Onsager's method for treating electrostatic inter- action.
Fluctuations are considered explicitly both in the orientation of an individual
dipole and in the local field acting on it ; a distinction is also made between
the experimentally measurable time constants and the relaxation times governing
molecular processes.
The results are presented m the form of a
series development in pourers of the dipolar concentration. In first
approximation the theory leads to a Debye frequency dependence of the
dielectric constant ; in second approximation a Debye dependence can be made
consistent with the molecular mechanism only for a more restricted
(two-position) model.
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50
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Sack RA. The Dielectric Properties of Systems Containing Straight Polar Chains. Aust J Chem 1952. [DOI: 10.1071/ch9520135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A mathematical derivation is given of the
dielectric properties of systems containing straight polar chains such that to
each value of the total moment of a chain there corresponds only one
arrangement of its dipoles. If the moments of the individual dipoles and the
probability of an elementary transition are fixed, both the total dielectric
loss and the effective relaxation time of the system increase in proportion to
the square of the number of states of each chain. These conclusions are not
valid for kinked chains and apply only qualitatively if the chains are
branched.
The theory provides an explanation for the
high dielectric losses at low frequencies observed in many solids containing
hydroxyl groups. It can further explain the low frequency absorption found in
ionic crystals containing lattice imperfections ; in this interpretation the
theory is related to Jaffe's theory of conductivity in polarizable media.
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